Electric furnace



Apfil 1s 1924.

1,490,207 0. A. COLBY ELECTRIC EURNACE Filed April 13, 1922 2 Shets-Sheet 1 I ll,

I I I l/ll/ INVENTOR Ora A. Colby;

/ ATTORNEY bril 1'5 1924.

o. A. COLBY,

ELECTRIC run'imcn Filed April 15, 1922 I! I! I? I II 2' sheata' slieet 2 I 7 ATTdRNEY Patented Apr. 15, 1924.

UNITED STATES mean? PATENT OFFHCE.

ORA. A. COLBY, 0F IRWIN, PENNSYLVANIA, ASSIGNOB T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRIC FURNACE.

Application filed April 13, 1922. Serial No. 552,179.

To allwhom it may concern:

Be it known that I, ORA A. COLBY, a citizen of the United States and a resident of Irwin, in the county of Westmoreland and State of Pennsylvania, have invented a'new and useful Improvement in Electric Furnaces, of which the following is a specification.

My invention relates to electric furnaces and particularly to electric-resistance furnaces and it has for one of its objects to provide a relativel inexpensive built-u refractory heating e ement for an electric resistance furnace.

Another object of my invention'is to provide a built-up refractory resistor having portions of curved form to permit of direet ing and concentrating the heat generated by said resistor agains't'an object prmaterial to beheated.- i

Another object of my inventi'on'is to pro vide a built-up refractory resistor having portions of curved form so connected that the current in adjacent portions flows in opposite directions and the current'path is relatively much longer than the length ofjthe resistor. v

Another obj ect'of my invention'i's' t'o' rovide resilient means to maintain the'portions of the'resistor in'close operative engagement.

Another object of my invention s to provide an electric-resistance furnace having, in addition to the resistor of the above indicated character, a second resistor connected in series circuit relatively to the first resistor and comprising a plurality of relatively thin, flat refractory plates resiliently maintained in close operative engagement with each other. 0 i

In ractising my invention, I provide a plurality of flat, relatively thin, refractory resistor members substantially semicircular in arcuate extent located in spaced-apart relation andelectrically connected at their ends in such manner that the current will traverse adjacent members inopposite directions. The individual members may be integral or may comprise a plurality of sections. The resistor members are supported by a portion of the refractory walls enclosing the furnace chamber, and a portion of the roof of the furnace chamber may be supported by the subdivided resistor members. Resilient mea ns are provided to maintain the ends of the adjacent resistor members in close operative engagement.

A second resistor may be located beneath the convex surface of the hcreinbefore described resistor members and may comprise aplurality of relatively thin refractory plates, the built-up resistor having substantially the same length as the first-mentioned resistor and electrically connected thereto at one end, the plates being maintained in close operativeengagement by resilient compressing means.

In the drawin I Figure l'is a view, in vertical lateral crosssection', of an electric-resistance furnace embodyin Fmyinvention, taken on the line Fig. 2'is a view, in vertical, longitudinal cross-section, of-a furnace taken on the line IBII of'Fig'. 1;

Fig. 3is a view, in vertical, lateral crosssection of an electric-resistance furnace embod 'ng'a modification of my invention;

1 ig. i is'a view, in vertical, longitudinal cross-section of the furnace illustrated in Fi 3, taken on the line IV'I V thereof.

ig. 5 is a view, in vertical, lateral crosssection' of another modification of my invention; y

Fig. 6 is a view, in vertical, longitudinal cross sectio'n ofthe furnaceillustrated in Fig. 5, taken on the line VIVI thereof;

Fig. 7 is a view, in side elevation, of a portion of a resistor member;

Fi 8 is a view, in side elevation, of the mem er illustrated in Fig. 7;

Fig. 9 is aview, in side elevation. of a resistor member of arena-to form em loyed to connect oppositely disposed members 11- lustrated inFig's, 'l'and 8;

Fi ltl is atop plan viewof the resistor mem er, illnstrated in Fig. 9 and Fig. 11 is a view,.in front elevation, of a still further modification ofa resistor member.

Referring particularly to Figs. 1 and 2.

of the drawings, an electric-resistance furnace, designated by the numeral 11, com-. prises a suitable metallic framework or skeleton 12, provided with supporting members 13 suitably secured thereto. in outer lining 14-, located within the framework .2, comprises a plurality of lnicks r blocks of a suitable hcahinsulating refrain-tony inn.- tcrial. An inner lining [5 comprises a plurality of bricks or blocks of a suitable refractory, high-temperature-resisting material usually em p'loyed in theart; the bricks or blocks constituting the two linings being so shaped and disposed as to provide a furnace chamber 16 of any suitable or desired contour and dimensions.

As it is desired to concentrate the h eat generated by the heating element located in asmay be notedqpartic,

- the top 'ofthe furnace chamber i6,,.with their lower or middle portions restinghupon suitable ledges 18 provided ,by the bi'i'cksfl -or blocks of the inner lining 15. .Inordeif to electrically connect the .spaced-apartiflinembers 17, connecting members 19 ofaarcuate form and of substantially the same radial width as the members .17 areieni'ployed; the end portions of the 'mem'bers19 bei providedwith a dovetail 21 whichien apted to interfit =with .acorresponding groove 21 providedin the upper ends of the vmembers 17.. When the members 19 are placed in their proper operative positions, with. their endsenga ing the ends ofthe members lfl, substantially. as illustrated in F ig; 1 of the drawings, a substantiall v self-supporting arch is provided ,by the uilt-u members 17 and 19. The members 17 on he opposite ledges 18 are located in staggered "relation relatively to each other; so that, when a plurality of members .17 and the C011? necting members 19 are built up,. substantially as illustrated in Figs. 1 and 2 of the drawings, the resistor members, consisting of two of the extensions of the members 17 and the intervening member 19, are in series-circuit relation with each other and these sets are in series-circuit relation with correspondin sets located adjacent thereto at each side t ereof. 'Refractor insulating blocks 22 are located between tiemembers 17 and are of a thickness substantially equal to the width of a slot 23 located between the two extensions of the members 17 In order to provide means to conduct current to and from the ends of the built-up heating element, I provide a refractor block 24 of suitable shape to engage the en members 17. Elongated refractory electrodes 25 extend respectively through each of two opposite furnace walls, their inner ends ongaging a depression in the outer surface of the terminal blocks 24 and carrying at their surface pf;

outer tapering ends metallic water-cooled electric-circuit terminal members 26. In order, to insulate the terminal members 26 from the furnace structure, I provide an annular insulating member 27 which may be of asbestos or other similar material and which is located in the surface of the fursite the furnace.

' Means v or-Pressing the terminal members 26Ion'thelelectrodefliand:the electrode 25 iiixieiPfid, with an enlarg flange Pbrtioirl zawb ph wea r-e againstfthqibltilYM l comprise a .screwthreaded -'st1 id,28 which. is provided, at its fame jdfga 'cplate ;31,o, f a; suitable: electrical located against" the outer V gthe"ieleetriocircu t,terminal 26. A -hjelicalifspring 32"is"ldcated around the member'28, 'and'a nut 33 and a washer 34 serye tocompress the sprin ,32 against a substantiallyfstationaryamem err-35., While l fhalye dicated a specific embodiment of "compr s ng n I o n t w I d 'theretog as any suitable or desired compressing 'ineans'may be employed. 'lhe construction of the electric-circuit terminalgli' and its mounting on the electrode 25 is i niore particularly described and claimed jinf a application, Serial endi Little; and; assigned to the Westinghouse Electric& Manufacturing Company v In order to permit of easy access to the furnace chamber 16, the roof is made substantially semicircular in contour and comprises twometal'members 36 provided with handles 37 which have a hinge connection on the metallic framework 12 as illustrated in Fig. 1 of the drawings. An outer layer 38 of any suitable heat-insulating material may be located within the cover members 36, and additional layers 39 and 41 of any suitable refractory heat-insulating and high temperature-resisting material may be located. inside of the lining 38. \Vhile the two layers 39 and 41 have been illustrated as being integral in construction, this is not an essential feature of my invention, as it is intended that these shall be built up in any suitable or desired manner, as usually employed in the art, so long as they serve the purpose .of not only covering the top of the furnace chamber but also of ermitting their being readily removed and replaced. The inner lining 41 may be provided with two relatively small integral extensions 42 so located as to operatircl engage the upper ends of the extensions of the members 17 to hold them in their proper operative positions, not only on the ledges 18 but also to cause the upper end of the members 17 to approach each other; and thereby to more closely engage the ends of the members 21. An opening 43 may be provided in one of the Walls of the furnace to permit of insorting material to be heat treated into the furnace chamber 16.

Referring more particmula-rly to Fi s. 3 and 4 of the drawings, Lhave .therein i lustrat-cd a modification of the hereinbefore described furnace in which the refractory resistor members are not built up of a plurality of parts'which are less than semicircular in arcuate extent. The heating element comprises a plurality of fiat refractory plates 44, substantially semicircular in arcuate extent, which are located in side-by-side relation. Refractory conducting blocks and refractory electricalinsulating blocks 46 are alternately located between two adjacent members 44, the construction being such that current will traverse the members 44 in series-circuit relation and flow'in opposite-directions in the adjacent members.- If desired, a plurality of members 44 and blocks 45.may be of integral construction, as --illustrated in Fig- 11- I "I: lu ..Means for-conductingcurrept to and from the heating, element comprise substantially, as hereinbefore -describ ed,-;.;a Irefractory terminal-block:.24 located ah;;.each endof the built-up heating element, 5 an, elongated refractory electrode 25,-: almetallic terminal member 26 operatively; I-cngagingthe, outer and th ereof and} a compressing 5 means indicatedjn :partonly but of vsulrstantiallyithe same; construction as. hereinbefore described in, connection-with; the furnaeei illustrated in Figs. 1 and 2. As'all of the otherzfeatures of the furnace amisubstantiallyas hereinh efore desoribedgit isnot deemed mecessary to describe them in further detail.

In.:-Figs; 5 -and 6',= is disclosed a heating element which comprises, in addition to that illustrated in Figs. 3 and 4, a heatin element located thereunder and connects in series-circuit relation therewith. A heating element 46 comprises a plurality of relatively thin, fiat, refractory substantially rectangular carbonaceous plates 47 having their flat faces in operative engagement with each other and being connected, at one end, in series-circuit relation with the adjacent end of the upper heating element by means of a refractory bar or plate 48. A substantially similar compressing means may be employed for the heating element 46, as is hereinbcfore described in connection with the heating element of substantially semiircular form. and it is believed that further description thereof is unnecessary. The built-up heating element, comprising a plurality of flat, carbonaceous plates resiliently compressed, is more particularly described and claimed in a copending application, Serial No. 454,776, filed March 23, 1921, by G. M. Little and assigned to the Westinghouse Electric & Manufacturing Company.

The heating -element comprising the members of substantially U-shape and the connecting members of arcuate form, as illustrated more particularly in Figs. 1 and 2 ofcrthe drawings, possesses the advantage that a= number. of contacts are provided between refractory materials and the individual members are relatively small in arcuate extent.

If it is found that the construction of the members 17 of substantially U-shape is relatlvely complicated and causes a loss by reason of fracture of some of the members during manufacturing operations, it' may be advisable to employ the relatively thin, flat arcuate member-s44 which may be easily-sawed from a relatively thick-walled tubular-; membcr.- .The: substantially semi: circular form of: the heating element 1 per.- mlts ofconcentrating a relatively large per.- centage ofthe hezitiati substantially the .center of -the are provided: by I theinner;isur face of the. upper heating'element, iwhereby zitrelatively high-temperatureii heat zone may be obtained. IfaEsti-lhhighen temperature-;.or-1a} greaterkamount fi heat;-is des red, then-modification i-llustrated in lFigs. ia dffi may1 be mplo edmAs hec r-r 1S i fct d l a e verse 'e' rintegial members 4 1;,-, a1 n;l the built l1P.mBm DI$i17-,:a.i1d 21' in SQIQQSflQJIGIJIt relation-,and'ztoc-fiow-ifrom one ide; qf-it aaf r qei ha berto the other them again-, thedsngth DIE-(Q18; curtapethi is'rre a i ely-i.il rge,,:as. compared e length-pf the. furnace chamber,

Where 'y- I aohtain; 2 a. relatively, ,high resist: a s for the entire current path,- thus, pen-i mattmg themse of a i supply circuit of .relat vely; high voltage and ,gelatiyely low cur-. ent QpBi'fai'n -u m funer -'1 main Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire that only such limitations shall be placed thereon as are imposed by the prior art or are specifically set forth in the appended claims.

I claim as my invention:

1. In an electric-resistance furnace, in combination, a plurality of refractory walls enclosing a furnace chamber, a heating element located in said chamber and comprising a plurality of curved and parallel-extending refractory members of substantially semicircular arcuate extent and having their lower ends supported by certain of said walls, refractory means located at one end of said curved members for electrically connecting them in series-circuit relation, refractory means located at the other ends of said curved members for maintaining them in substantially parallel relation, terminal electrodes having one end extending through one of said walls and ogeratively engagin said heating element, an resilient means or maintaining said electrodes in close operative engagement with said heat ing element.

2. In an electric-resistance furnace, in combination, a plurality of refractory walls enclosing a furnace chamber, a heating ele ment located in said chamber and com rising a plurality of curved and paralle -extending refractory members of substantially semicircular arcuate extent and having their lower ends supported by certain of said walls, refractory means located at one end of said curved members for electrically connecting them in series-circuit relation, refractory means located at the other end of said curved members for maintaining them in substantially parallel relation, terminal blocks located partly beneath and partly at the side of the end refractory members and operatively engaging the same, terminal electrodes operative y engaging said terminal blocks and resilient means for pressing said electrodes, terminal'blocks and refractory members in close operative engagement.

'3. In an electric-resistance furnace, in combination, a plurality of refractory walls enclosing a furnace chamber, a heating element located in said chamber andcomprising a plurality of curved and parallel-extending refractory members of substantially semicircular arcuate extent and having their lower ends supported by certain of saidwalls, refractory meanslocated at one; end of said curved members for electrically connecting them'in; series-circuit re lation, refractory means located atthe other end of said curved members for maintaining them in substantially parallel relation, :1. second heating element comprising a plurality of relatively thin flat refractory plates having their flat faces in operative engagement and located beneath said first named heating element and substantially coextensive therewith, a refractory member for connecting: the two heating elements in series-circuit relation, terminal electrodes operatively engaging said heating elements and resilient means for pressing said electrodes into close operative engagement with said heating elements.

4:. In an electric-resistance furnace, in

combination, a plurality of refractory walls enclosing a furnace chamber, a heating element supported by certain of said walls and comprising a plurality of refractory members each having a pair of parallel-extending curved portions of substantially semicircular arcuate extent, means for so connecting the curved portions of successive refractory members that an -electric current will traverse the adjacent portions in opposite directions and resilient means for causing said connecting means to closely engage said refractory members. 5. In an electric-resistance furnace, in combination, a plurality of refractory walls enclosing a furnace chamber, a heating element supported by certain of said walls and comprising-a plurality of refractory members each having a pair of parallel-extendingcurved portions of substantially-semicircular arcuate extent, means for so connecting the curved portions of successive refractory members that an electric current will traverse the adjacent portions in opposite directions, resilient means for causing said connecting means to closely enga said refractory members, and a roof for said furnace chamber partly supported by said heating element.

In testimony whereof, I have hereunto subscribed my name this 11th day of April,

1922. ORA A. COLBY. 

